How to read battery characteristics using boron

i have heart rate sensor and i am able to read heart rate measurement using boron. battery services is also present in this heart rate sensor and now i want to read battery level of heart rate sensor, how can i do that?

Hi @pisquaretech, have you tried going to Console > Devices > Vitals > Battery Life.

I want to read battery characteristic of heart rate sensor connected to boron, not battery characteristic of boron.


A simple way to do this is with the same chip that the Particle Boron uses, the Maxim Integrated MAX17043 - LiPo Fuel Gauge.

The chip itself is very small and is placed in-line with the battery being monitored. Here is a small board I used for this purpose. Happy to share the EAGLE files if you are interested. Then, you simply monitor the state of charge via i2c. You will need a second i2c bus as the i2c address is fixed. ;-(

Hope this helps,


@chipmc, he wants to read the battery characteristic of a BLE heart monitor via BLE, not the Boron’s battery. @pisquaretech, I suggest you do a search of the forum to look for some hints on discovering the battery characteristic’s UUID so you can read it. You may want to start with connecting to your sensor using the nRF Connect app.



Sorry if I was not clear. The little board I showed above would be put in-line between the BLE heart rate monitor and its (assumed) LiPo battery. I have used this to monitor other external LiPO batteries in other projects.

Your approach seems to be to connect to the heart rate monitor via Bluetooth and this is likely a cleaner approach and the only one if the monitor is a sealed unit and you cannot get between it and its battery.



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It should be pretty much the same as how you’re reading the heart rate. Just read characteristic 0x2a19 (battery level) instead of the heart rate characteristic 0x2a37. Battery level is always one byte (0-100) instead of the heart rate that can be 1 or 2 bytes.


The body temperature example in the docs does show how to expose the battery level characteristic. From that (in combination with the heart rate central sample) you may get a feeling of how to read it.


ok thanks for your reply @rickkas7 . but battery characteristics has only read property. so which call back function should i implement. onDataRecived will work?